Re: security: restricting access to swap

[Will Drewry <wad@chromium.org>]

KOSAKI Motohiro <kosaki.motohiro <at> gmail.com> writes:

> 
> (3/11/13 7:57 PM), Luigi Semenzato wrote:
> > Greetings linux-mmers,
> > 
> > before we can fully deploy zram, we must ensure it conforms to the
> > Chrome OS security requirements.  In particular, we do not want to
> > allow user space to read/write the swap device---not even root-owned
> > processes.
> 
> Could you explain Chrome OS security requirement at first? We don't want
> to guess your requirement.

I'll try to add a little more flavor. We're continuing to reduce the
exposure from root-equivalent users wherever possible.  Enabling swap
support to a block device means an alternative means to access/modify
swapped out user-context  memory with a single discretionary access
control check, bypassing any per-process checks in /proc/<pid>/mem
(like mm_open(..., PTRACE_MODE_ATTACH)), and so on.

hth!
will

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